I run Ubuntu 14.04 and a LAMP stack. I'm having strange issues with my Joomla site and I suspect that maybe it's because of my errors in running a web server. I'm getting a wrong addresses when I create new menu items (A strange directory "Feeds" appears and I see just the main Joomla page)

If I recall correctly, when I created my original Joomla site in J 1.5 I did use .htaccess in my Joomla root and I chose an appropriate option in Joomla admin panel. Another important point is that I built an original site in a hosting environment (ie, on a distant server, probably running PHP 5.3 I would assume). I'm not an expert in Apache, but I think that I must use a certain directive to enable use of .htaccess (I think it's disabled by default). I haven't enabled it. The reason why I even decided to upgrade my Joomla installation from J 1.5 to 2.5 is because I had issues when I tried to add a payment module in Virtuemart and I thought that maybe the reason was because of incompatibility of J 1.5 and PHP 5.5 (it's a default PHP version under Ubuntu 14.04). And though I did successfully an upgrade of Joomla version from 1.5 to 2.5, after that I couldn't open any of my menu items (except for the home page). I was getting 404 errors everywhere! And then I turned off my "Use URL rewriting" option and renamed back .htaccess to htaccess.txt And after that everything got back to normal (everything that was already there, not NEW menu items -- I simply didn't create any new menu items at THAT point in time).
Of course, I can wait till J 3.5 appears (I prefer to use LTS versions of everything) and then to re-build a site from scratch (or maybe to upgrade Joomla AGAIN from 2.5 to 3.5), but I don't want to just jump into those kind of extreme solutions, especially when they're so TIME CONSUMING (to build a site from scratch).
What I'm trying to ask here... Maybe I should just enable .htaccess use in Apache to avoid those kind of issues?

The problem is solved. It was a Joomla/Virtuemart issue, not really a web server problem. Had to go to Menu manager in Joomla and press Rebuild button there to get menu items in order.
Anyone can explain at least what's going on?